A multidisciplinary approach to the study of AID/Kaposi's sarcoma patients is described. Studies will be carried out to compare three types of patients to determine if they have the same basic disease state. The three groups of patients to be sutdied are: (1) homosexual males with AID and/or Kaposi's sarcoma, (2) presumably heterosexual Haitian males who appear to have a similar disease characterized by opportunistic infections and/or Kaposi's sarcoma, and (3) hemophiliacs who have been receiving large volumes of unsterlized blood products (factor VIII). Recently several cases of an AID-like illness have been described among such hemophiliacs. These groups of patients will be evaluated with respect to (1) immune function, (2) macrophage function, and (3) possible viral etiology. The regulation of the immune response in these patients will be examined by in depth studies in three areas: (1) the generation of immune suppressive factors by their peripheral blood mononuclear cells, (2) the generation of helper an/or suppressor activity in autologous mixed lymphocyte reaction and (3) the presence of circulating antigen-antibody complexes. Macrophage function will be examined in respect to: (1) intracellular microbicidal activity, (2) activation of macrophages by lymphokines, (3) differentiation of macrophages and (4) function of macrophages in granuloma formation. Viral studies include attempts to demonstrate the presence of viral DNA in lymph nodes from AID patients using human CMV, simian CMV, human EBV and Herpes-simplex virus and restriction enzyme cleaved DNA and multiple different cloned viral DNA fragments as probes. Expression of viral specific antigens in cells from AID patients and the ability of T-cells from AID patients to control the proliferation of EBV-infected cells will also be studied. Tissues from Kaposi's sarcoma patients will also be studied.